Optimized thread profile for joining composite materials

Abstract

An optimized thread profile (140) for joining composite materials is presented. This thread profile (140) maintains a certain material strength when used as part of a composite threaded joint (101). The thread profile (140) comprises a repeating pattern of four components: a crest region (150), a first flank (162), a root region (170) and a second flank (164). The thread profile (140) is symmetrical, that is, the dimensions of the four components do not change throughout the length of the thread profile. The crest (152) has a flat profile and the root (172) has a rounded profile. When a shaft (120) is affixed to a joining shaft (110) using this optimized thread profile (140), the flat profiles of the crest (152) of the shaft (120) and corresponding rounded profiles of the root (172) of the joining shaft (110) create a gap to accommodate a substance such as an adhesive or a lubricant. Similarly, the flat profiles of the crest (152) of the joining shaft (110) and corresponding rounded profiles of the root (172) of the shaft (120) create a gap to accommodate a substance.

I claim: 
     
       1. A shaft, the shaft comprising:
 (a) a thread profile, the thread profile comprising of a repeating pattern of:
 (i) a crest region; the crest region comprising:
 (1) a crest; 
 (2) a first crest transition; 
 (3) a second crest transition; 
 
 (ii) a first flank; 
 (iii) a root region; the root region comprising:
 (1) a root; 
 (2) a first root end; 
 (3) a second root end; 
 
 (iv) a second flank; 
 (v) where the root joins the first flank at the second root end, 
 (vi) where the root joins the second flank at the first root end, 
 (vii) where the first crest transition joins the crest with the first flank, 
 (viii) where the second crest transition joins the crest with an adjacent second flank, 
 (ix) where the root has a rounded profile and the radius of the root is 0.060°, 
 (x) where the crest has a flat profile, 
 (xi) where the first crest transition and the second crest transition have a rounded profile and the radius of the rounded profile is 0.010°, 
 (xii) where the thread angle between the first flank and the second flank is 90° plus or minus 10°; 
 
 (b) a threaded portion following the thread profile. 
 
     
     
       2. The shaft as defined in  claim 1 ,
 (a) where the shaft is made from composite materials. 
 
     
     
       3. The shaft as defined in  claim 2 ,
 (a) wherein the composite materials of the shaft are epoxy resin and glass fiber. 
 
     
     
       4. A threaded joint tool comprising:
 (a) a thread profile, the thread profile comprising of a repeating pattern of:
 (i) a crest region; the crest region comprising:
 (1) a crest; 
 (2) a first crest transition; 
 (3) a second crest transition; 
 
 (ii) a first flank; 
 (iii) a root region; the root region comprising:
 (1) a root; 
 (2) a first root end; 
 (3) a second root end; 
 
 (iv) a second flank; 
 (v) where the root joins the first flank at the second root end, 
 (vi) where the root joins the second flank at the first root end, 
 (vii) where the first crest transition joins the crest with the first flank, 
 (viii) where the second crest transition joins the crest with an adjacent second flank, 
 (ix) where the root has a rounded profile and the radius of the root is 0.060°, 
 (x) where the crest has a flat profile, 
 (xi) where the first crest transition and the second crest transition have a rounded profile and the radius of the rounded profile is 0.010°, 
 (xii) where the thread angle between the first flank and the second flank is 90° plus or minus 10°; 
 
 (b) a shaft, the shaft comprising a threaded portion following the thread profile; 
 (c) a joining shaft, the joining shaft comprising of:
 (i) an exterior surface; and 
 (ii) an interior surface, the interior surface comprising a threaded portion following the thread profile; 
 
 (d) where the shaft is affixed to the joining shaft. 
 
     
     
       5. The threaded joint tool as defined in  claim 4 ,
 (a) where the shaft and the joining shaft are made from composite materials. 
 
     
     
       6. The threaded joint tool as defined in  claim 5 ,
 (a) wherein the composite materials of the shaft are epoxy resin and glass fiber. 
 
     
     
       7. The threaded joint tool as defined in  claim 4 ,
 (a) where the either the shaft or the joining shaft is made from composite materials and the other is made from non-composite materials. 
 
     
     
       8. The threaded joint tool as defined in  claim 4 , the threaded joint tool further comprising:
 (a) a gap; 
 (b) where the gap is created
 (i) between the flat profiles of the crests of the shaft and corresponding rounded profiles of the roots of the joining shaft, and 
 (ii) between the flat profiles of the crests of the joining shaft and corresponding rounded profiles of the roots of the shaft, 
 
 (c) where the gap accommodates a substance such as adhesive or lubricant.